1. Field of the Invention
The present invention is related to a portable electrical adapter, and more particularly to an electrical adapter which can be assembled with various plugs.
2. Description of Related Art
Because AC voltage supplies in various countries are different, a traveller often has to carry a portable electrical adapter for using electrical appliances such as a mobile phone, a shaver, etc. Furthermore, as electric outlets also have various configurations, the electrical adapter often provides a detachable plug. A conventional electrical adapter being composed of a detachable plug (80) and a transformer (90) is shown in FIGS. 6-10.
Referring to FIGS. 6-7, the detachable plug (80) has two first blades (88) extending through a front part (81) thereof. A block (82) is provided at a rear end of the plug (80) and two sockets (84) are defined through a bottom thereof The transformer (90) has a notch (92) defined therein and two second blades (94) are pivotally mounted at a bottom of the notch (92). When the second blades (94) are pivoted up to be received in the notch (92), as shown in FIG. 6, the plug (80) can be attached on the transformer (90) with the block (82) received in the notch (92) and first ends of the second blades (94) are inserted in the sockets (84). A user can change different plugs (80) with various blades (88) according to various outlets.
Referring to FIGS. 7 and 8, the plug (80) further has a back plate (85) provided at a rear surface of the front part (81). Two first conductive strips (83) are provided in the plug (80) and each has a first sheet (830) electrically connected with the respective first blade (88) and a V-like leaf (832) received in the respective socket (84). The second blades (94), which are inserted in the sockets (84), are clamped by the leaves (832).
In a case that the electrical adapter is plugged in a outlet on a wall, because of the weight of the transformer (90), the second blades (94) can disengage from the V-like leaves (832) and the transformer (90) will drop from the outlet. Thus, a metal material used to make the V-like leaf (832) must be thick enough to provide adequate clamping force for the second blades (94) to overcome the weight of the transformer (90). However, it is difficult for a user to insert the second blades (94) in the leaves (832) with high clamping force if the leaves (832) are too thick. Moreover, after long term detaching and attaching, the leaves (832) will be worn and the clamping force thereof will be reduced.
Referring to FIGS. 9 and 10, the transformer (90) has two slots (920) respectively defined at two sides of the notch (92). A bottom channel (96) is defined at a bottom of the notch (92) and in communication with the slots (920). An axle (940) is provided between second ends of the second blades (94). Two contactors (942) are respectively formed at outer surfaces of the second ends of the second blades (94). A U-like fastener (960) formed with two lateral plates and an upright plate is provided in the bottom channel (96) to clamp the axle (940) between the lateral plates. Distal ends of the lateral plates of the U-like fastener (960) are integrated with the housing of the transformer (90) by means of hot-melting.
Two second conductive strips (98) are provided in the housing of the transformer (90) and each has a second sheet (980) fixed in the housing and a finger (984) extending out from the respective slot (920). The second sheets (980) are electrically connected with a circuit board (not shown) and each has an orifice (982) defined therein for a pole (not shown or numbered) in the housing to extend therethrough. Distal ends of the poles are expanded by means of hot-melting to fix the sheets (980) on the poles. The fingers (984) each have a hook (986) formed at a distal end thereof and electrically connected with the respective contactor (942).
Because the transformer (90) is made by means of hot-melting, special machining tools for hot-melting must be provided for the process, which increases manufacturing cost and is inefficient. Furthermore, there are two "contact-points" between each of second blades (94) and the circuit board, wherein one is between the circuit board and the sheet (980), and the other is between the hook (986) and the contactor (942). Thus, a conductivity of the electrical adapter is low, and a failure rate is high.
Therefore, the invention provides an improved electrical adapter to mitigate and/or obviate the aforementioned problems.